The invention relates to a bundle and a method for producing the bundle for which a plurality of print sheets or signatures are combined into a book block and for which a plurality of book blocks, having the same orientation and respectively positioned standing upright on the lower edges of the print sheets, are combined into a quadrangular-shaped bundle with two end faces and two side surfaces, as well as an upper and a lower surface. The book blocks are then compressed and are secured in position following the compressing. Bundles of this type are produced for the temporary storage of print sheets with the aid of so-called bundle delivery machines. For this, print sheets which are successively lined up while positioned upright are gathered, compressed, and then strapped together to form a bundle.
As is known, for the production of perfect-bound or adhesive-bound printed products such as books, paperback books and similar products, the required print sheets and covers are printed during a first step in an optional sequence and are then stored temporarily. The print sheets, for example identical or different type sheets which can also be folded individual sheets, single pages, inserts and supplements, fly leaves or sheets with glued-on fly leaves, are subsequently gathered in the correct sequence to form loose book blocks and are then supplied to a perfect binder to be bound along the spine and glued together with additional book components, such as covers, book cases for hardcover products, combination fly leaves or reinforcing strips. By separating the printing process from the binding process, each process can be realized with the correspondingly optimum speed. However, it has proven to be a disadvantage that the binding process can be carried out only if all print sheets and covers have already been printed, which requires a relatively large area for storing the print sheets and covers.
Also known are printing presses which sequentially print all pages of a book and subsequently deliver complete, loose book blocks that can be supplied directly to a perfect binder. A printing press of this type is known from the document U.S. Pat. No. 3,518,940. With this method, which is rarely used in practical operations, the temporary storage of print sheets can be avoided, but it also requires an extremely involved printing press. In addition, this method makes economic sense only for extremely large editions and the achievable print quality is low.
For some time now, digital printing presses have been known which sequentially print all pages of a book and then supply complete, loose book blocks that can be bound without requiring further operations. A digital printing press accordingly can be used to optionally produce sequentially-printed, complete book blocks which contain different contents. A further advantage of the digital printing press is that no printing plates are required. In addition to avoiding the costs of producing the printing plates, the interruptions in the operation required for replacing the printing plates are also omitted. The print sheets or individual pages that form a book block are delivered in the form of a stack, for example deposited in an offset arrangement on a pallet, so that they can be separated again easily later on. Alternatively, non-offset layers of book blocks can be formed, meaning these layers are stacked one above the other, by inserting intermediate layers for separating them. Book blocks stacked in this way can be stored for an optional length of time before being supplied to a perfect binder.
The stacking of the loose stacks on the pallets can either be carried out manually or automatically, with the aid of a so-called palletizer. A device of this type is disclosed in European patent document EP 2098465 A1. The loose sheet stacks of horizontally positioned printed products are removed again manually from the pallet at a later time and are supplied to the feeding region of a perfect binder. However, this solution has the known disadvantage that the loose book blocks are not sufficiently compressed along the fold region, thereby resulting in products which are considerably thicker in the fold region than in the flat region. In addition, the book blocks on the bottom are compressed most and the top ones are not compressed at all. Poorly compressed book blocks or differently strong compressed book blocks can lead to serious problems during the further processing or can hinder the further processing.
European patent document EP 2159070 A1 proposes gluing together the print sheets in a stack along one edge region. As a result, the stacks can be separated again clearly at a later point in time, prior to the further processing. With this method, however, the print sheets are also compressed irregularly or insufficiently, thereby again resulting in the previously mentioned disadvantages. The glued together print sheets furthermore can no longer be aligned, relative to each other, in the perfect binder. A further disadvantage is that the surface area of the print sheets which is necessary for the gluing and which must then be cut off in a three-knife trimmer during the final trimming step considerably increases the use of paper. An additional disadvantage is the thickening of the stack in those locations where adhesive is applied to the print sheets, thereby making the further processing more difficult.
Also known is a method of gluing the print sheets together along the front ends rather than between the flat areas. Besides the above-mentioned disadvantages of such a gluing operation, this method has the further disadvantage that glue can be deposited along the paper guides during the further processing, thereby causing machine malfunctions and necessitating the expense of a cleaning operation.
Instead of depositing the stacks of print sheets on pallets or similar devices, methods are furthermore known for which the printing press is arranged and operated in line with the perfect binder. Since the printing press can print continuously, as previously mentioned, a buffer or storage section must be provided between the printing press and the further processing locations, wherein the buffer capacity must be sufficient for the individual storage of the book blocks which are printed during the period of changeover to the further processing operations. Additional buffer capacity should also be provided in case the further processing operation stops for any reason whatsoever. Alternatively, the book blocks printed during such an interval can also be transferred out and can then be re-supplied at a later time.
The European patent document EP 1950159 A1 discloses a stack-type arrangement of flat printed products, wherein all printed products within the stack have the same orientation. One of the four sides of the printed products is thicker than the other sides, for example because the printed products have a fold or even a staple on this side. To ensure that these stacks have the same stability as the stacks composed of partial stacks which are arranged offset to each other by 180°, the partial stacks in this case are arranged so as to alternate the thicker sides. In the process, the partial stacks are offset perpendicular to the lower edges, in the direction of the stack height. Stacks configured in this way have the disadvantage that the printed products within the stack are compressed differently strong in the region of the thicker side, thereby causing the non-compressed fold regions to have a tendency to fan out.